Active noise cancellation (ANC) systems commonly operate by sensing ambient noise through a reference microphone and generating a corresponding anti-noise signal that is approximately equal in magnitude, but opposite in phase, to the sensed ambient noise. The ambient noise and the anti-noise signal cancel each other acoustically, allowing the user to hear only a desired audio signal. To achieve this effect, a low-latency, programmable filter path from the reference microphone to a loud-speaker that outputs the anti-noise signal may be implemented. In operation, conventional anti-noise filtering systems do not completely cancel all noise, leaving residual noise and/or generating audible artefacts that may be distracting to the user.
Unlike ambient noise, wind noise occurs at the reference microphone due to local air turbulence and is not correlated to the ambient noise that reaches the ear canal. Wind noise degrades ANC performance in at least two respects. First, wind noise typically passes through the adaptive filter and will be audible to the user. Second, the presence of wind noise can result in an incorrect reference signal, anti-noise signal and/or incorrect adaption of the ANC filter.
In view of the foregoing, there is a continued need for improved active noise cancellation systems and methods for headphones, earbuds and other personal listening devices that may operate in windy environments.